TY - JOUR A1 - Richter, Maria A1 - Güttler, Arne A1 - Pauli, Jutta A1 - Vogel, K. A1 - Homann, Christian A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Extending certified spectral fluorescence standards for the calibration and performance validation of fluorescence instruments to the NIR—closing the gap from 750 to 940 nm with two novel NIR dyes N2 - Fluorescence techniques such as fluorescence spectroscopy, microfluorometry, and fluorescence microscopy, providing spectral, intensity, polarization, and lifetime information, are amongst the most broadly utilized analytical methods in the life and materials sciences. However, the measured fluorescence data contain sample- and instrument-specific contributions, which hamper their comparability across instruments and laboratories. Comparable, instrument-independent fluorescence data require the determination of the fluorescence instrument’s wavelength-dependent spectral responsivity, also termed emission correction curve, for the same instrument settings as those used for the fluorescence measurements as a prerequisite for the subsequent correction of the measured instrument-specific data. Such a spectral correction is essential for the performance comparison of different fluorescent labels and reporters, quantitative fluorescence measurements, the determination of the fluorescence quantum yield, and the spectroscopic measure for the fluorescence efficiency of a fluorophore. Simple-to-use tools for obtaining emission correction curves are chromophore-based reference materials (RMs), referred to as fluorescence standards, with precisely known, preferably certified instrument-independent fluorescence spectra. However, for the increasingly used near-infrared (NIR) wavelength region >700 nm, at present, no spectral fluorescence standards are available. To close this gap, we developed two novel spectral fluorescence standards, BAM F007 and BAM-F009, with broad emission bands from about 580 to 940 nm in ethanolic solution. These liquid fluorescence standards currently under certification, which will be released in 2025, will expand the wavelength range of the already available certified Calibration Kit BAM F001b-F005b from about 300–730 to 940 nm. In this research article, we will detail the criteria utilized for dye and matrix selection and the homogeneity and stability tests accompanying dye certification as well as the calculation of the wavelength-dependent uncertainty budgets of the emission spectra BAM F007 and BAM-F009, determined with the traceably calibrated BAM reference spectrofluorometer. These fluorescence standards can provide the basis for comparable fluorescence measurements in the ultraviolet, visible, and NIR for the fluorescence community. KW - Quality assurance KW - Reference material KW - Fluorescence KW - Dye KW - Traceability KW - Metrology KW - Calibration KW - Reference data KW - Reference product KW - Digital certificate KW - NIR KW - Instrument performance validation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626317 DO - https://doi.org/10.1007/s00216-024-05723-w SN - 1618-2650 SP - 1 EP - 15 PB - Springer AN - OPUS4-62631 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huber, Alexandra A1 - Behnke, Thomas A1 - Würth, Christian A1 - Jäger, Christian A1 - Resch-Genger, Ute T1 - Spectroscopic characterization of coumarin-stained beads: quantification of the number of fluorophores per particle with solid-state 19F-NMR and measurement of absolute fluorescence quantum yields N2 - The rational design of nano- and micrometer-sized particles with tailor-made optical properties for biological, diagnostic, and photonic applications requires tools to characterize the signal-relevant properties of these typically scattering bead suspensions. This includes methods for the preferably nondestructive quantification of the number of fluorophores per particle and the measurement of absolute fluorescence quantum yields and absorption coefficients of suspensions of fluorescent beads for material performance optimization and comparison. Here, as a first proof-of-concept, we present the first time determination of the number of dye molecules per bead using nondestructive quantitative (19F) NMR spectroscopy and 1000 nm-sized carboxylated polystyrene particles loaded with varying concentrations of the laser dye coumarin 153 containing a CF3 group. Additionally, the signal-relevant optical properties of these dye-loaded particles were determined in aqueous suspension in comparison to the free dye in solvents of different polarity with a custom-built integrating sphere setup that enables spectrally resolved measurements of emission, transmission, and reflectance as well absolute fluorescence quantum yields. These measurements present an important step toward absolute brightness values and quantitative fluorescence analysis with particle systems that can be exploited, for example, for optical imaging techniques and different fluorescence assays as well as for the metrological traceability of fluorescence methods. PY - 2012 DO - https://doi.org/10.1021/ac3000682 SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 8 SP - 3654 EP - 3661 PB - American Chemical Society CY - Washington, DC AN - OPUS4-25873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Resch-Genger, Ute A1 - Richter, Maria A1 - Güttler, Arne A1 - Pauli, Jutta A1 - Vogel, K. A1 - Homann, Christian A1 - Würth, Christian T1 - Extending Certified Spectral Fluorescence Standards for the Calibration and Performance Validation of Fluorescence Instruments to the NIR – Closing the Gap from 750 nm to 940 nm with Two Novel NIR Dyes N2 - Fluorescence methods provide spectral, intensity, polarization, and lifetime information, which contain sample- and instrument-specific contributions. Fluorescence data, comparable across instruments and laboratories, require validated calibration procedures and certified fluorescence standards. KW - Quality assurance KW - Reference material KW - Fluorescence KW - Dye KW - Traceability KW - Metrology KW - Calibration KW - Reference data KW - Reference product KW - Digital certificate KW - NIR KW - Instrument performance validation PY - 2025 SP - 1 EP - 4 PB - Springer Nature CY - London AN - OPUS4-62739 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hennig, Andreas A1 - Borcherding, H. A1 - Jäger, Christian A1 - Hatami, Soheil A1 - Würth, Christian A1 - Hoffmann, Angelika A1 - Hoffmann, Katrin A1 - Thiele, T. A1 - Schedler, U. A1 - Resch-Genger, Ute T1 - Scope and limitations of surface functional quantification methods: exploratory study with poly(acrylic acid)-grafted micro- and nanoparticles N2 - The amount of grafted poly(acrylic acid) on poly(methyl methacrylate) micro- and nanoparticles was quantified by conductometry, 13C solid-state NMR, fluorophore labeling, a supramolecular assay based on high-affinity binding of cucurbit[7]uril, and two colorimetric assays based on toluidine blue and nickel complexation by pyrocatechol violet. The methods were thoroughly validated and compared with respect to reproducibility, sensitivity, and ease of use. The results demonstrate that only a small but constant fraction of the surface functional groups is accessible to covalent surface derivatization independently of the total number of surface functional groups, and different contributing factors are discussed that determine the number of probe molecules which can be bound to the polymer surface. The fluorophore labeling approach was modified to exclude artifacts due to fluorescence quenching, but absolute quantum yield measurements still indicate a major uncertainty in routine fluorescence-based surface group quantifications, which is directly relevant for biochemical assays and medical diagnostics. Comparison with results from protein labeling with streptavidin suggests a porous network of poly(acrylic acid) chains on the particle surface, which allows diffusion of small molecules (cutoff between 1.6 and 6.5 nm) into the network. KW - Polymers KW - Surface groups KW - Quantification KW - Fluorescence PY - 2012 DO - https://doi.org/10.1021/ja302649g SN - 0002-7863 SN - 1520-5126 VL - 134 IS - 19 SP - 8268 EP - 8276 PB - American Chemical Society CY - Washington, DC AN - OPUS4-26002 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Time resolved spectroscopy of upconverting lanthanide based upconversion nanocrystals N2 - The optical properties of these materials strongly depend on the excitation power density, i.e., the number of photons absorbed per time interval. The upconversion quantum efficiencies (ΦUC) of these materials, the excitation power dependent population i.e. the emission characteristics, and the deactivation dynamics are influenced by nanoparticle architecture, doping concentration, and the microenvironment. We will discuss how time resolved measurements can help to understand the fundamental photophysical mechanisms and discuss differences to other nanocrystals like quantum dots. T2 - 19th International Course on “Principles and Applications of Time-resolved Fluorescence Spectroscopy” CY - Berlin, Germany DA - 16.11.2022 KW - Nanoparticle KW - Lanthanide KW - Upconversion KW - Energy transfer PY - 2022 AN - OPUS4-57000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Relative and absolute determination of the quantum efficiency of transparent and scattering luminescent materials T2 - Institutsseminar Werkstoffwissenschaften Universität Erlangen CY - Erlangen, Germany DA - 2014-06-23 PY - 2014 AN - OPUS4-30919 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Scattering of Particles N2 - Introduction to theory and applications of light scattering T2 - Cost-action Training school CY - Turku, Finland DA - 03.04.2017 KW - Light scattering PY - 2017 AN - OPUS4-40010 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Spektroskopie mit der Ulbrichtkugel: Streuende und floureszierende Systeme in der Bioanalytik T2 - PTB-Institutsseminar CY - Braunschweig, Germany DA - 2013-01-23 PY - 2013 AN - OPUS4-27806 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Time resolved spectroscopy of upconverting lanthanide based upconversion nanocrystals N2 - This presentation gives an overview of time correlated population and depopulation processes of the electronic states of lanthanide doped nanoparticles. The fundamental principles of sensitized photon upconversion are explained. Theoretical principles and the correlation to experimental results are shown. Examples are given for particle growth, dissolution as well as influences of size, doping concentration and microenvironment. T2 - Principles and Applications of Time-resolved Fluorescence Spectroscopy CY - Berlin, Germany DA - 12.11.2024 KW - Upconversion KW - Time domain PY - 2024 AN - OPUS4-61652 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grauel, Bettina A1 - Würth, Christian A1 - Homann, C. A1 - Krukewitt, Lisa A1 - Andresen, Elina A1 - Roik, Janina A1 - Recknagel, Sebastian A1 - Haase, M. A1 - Resch-Genger, Ute T1 - Volume and surface effects on two-photonic and three-photonic processes in dry co-doped upconversion nanocrystals N2 - Despite considerable advances in synthesizing high-quality core/shell upconversion (UC) nanocrystals (NC; UCNC) and UCNC photophysics, the application of near-infrared (NIR)-excitable lanthanide-doped UCNC in the life and material sciences is still hampered by the relatively low upconversion luminescence (UCL) of UCNC of small size or thin protecting shell. To obtain deeper insights into energy transfer and surface quenching processes involving Yb3+ and Er3+ ions, we examined energy loss processes in differently sized solid core NaYF4 nanocrystals doped with either Yb3+ (YbNC; 20% Yb3+) or Er3+ (ErNC; 2% Er3+) and co-doped with Yb3+ and Er3+ (YbErNC; 20% Yb3+ and 2% Er3+) without a surface protection shell and coated with a thin and a thick NaYF4 shell in comparison to single and co-doped bulk materials. Luminescence studies at 375 nm excitation demonstrate backenergy transfer (BET) from the 4G11/2 state of Er3+ to the 2F5/2 state of Yb3+, through which the red Er3+ 4F9/2 state is efficiently populated. Excitation power density (P)-dependent steady state and time-resolved photoluminescence measurements at different excitation and emission wavelengths enable to separate surface-related and volume-related effects for two-photonic and threephotonic processes involved in UCL and indicate a different influence of surface passivation on the green and red Er3+ emission. The intensity and lifetime of the latter respond particularly to an increase in volume of the active UCNC core. We provide a threedimensional random walk model to describe these effects that can be used in the future to predict the UCL behavior of UCNC. KW - Nano KW - Nanomaterial KW - Upconversion KW - Nanoparticle KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Pphotophysics KW - Lifetime KW - Sensor KW - Excitation KW - Power density KW - Single particle KW - Brightness KW - NIR KW - Mechanism KW - Modeling KW - Simulation KW - Energy transfer PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-535317 DO - https://doi.org/10.1007/s12274-021-3727-y SN - 1998-0124 VL - 15 IS - 3 SP - 2362 EP - 2373 PB - Springer AN - OPUS4-53531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geißler, Daniel A1 - Würth, Christian A1 - Wolter, C. A1 - Weller, H. A1 - Resch-Genger, Ute T1 - Excitation wavelength dependence of the photoluminescence quantum yield and decay behavior of CdSe/CdS quantum dot/quantum rods with different aspect ratios N2 - The excitation wavelength (lexc) dependence of the photoluminescence (PL) quantum yield (FPL) and decay behavior (tPL) of a series of CdSe/CdS quantum dot/Quantum rods (QDQRs), consisting of the same spherical CdSe core and rod-shaped CdS shells, with aspect ratios ranging from 2 to 20 was characterized. lexc between 400–565 nm were chosen to cover the first excitonic absorption band of the CdSe core material, the onset of absorption of the CDs shell, and the region of predominant shell absorption. A strong lexc dependence of relative and absolutely measured FPL and tPL was found particularly for the longer QDQRs with higher aspect ratios. This is attributed to combined contributions from a length-dependent shell-to-core exciton localization efficiency, an increasing number of defect states within the shell for the longest QDQRs, and probably also the presence of absorbing, yet non-emitting shell material. Although the FPL values of the QDQRs decrease at shorter wavelength, the extremely high extinction coefficients introduced by the shell outweigh this effect, leading to significantly higher brightness values at wavelengths below the absorption onset of the CdS Shell compared with direct excitation of the CdSe cores. Moreover, our results present also an interesting example for the comparability of absolutely measured FPL using an integrating sphere setup and FPL values measured relative to common FPL standards, and underline the Need for a correction for particle scattering for QDQRs with high aspect ratios. KW - Quantum dot KW - Quantum rod KW - Quantum yield KW - Integrating sphere KW - Decay time PY - 2017 DO - https://doi.org/10.1039/C7CP02142A SN - 1463-9076 SN - 1463-9084 VL - 19 IS - 19 SP - 12509 EP - 12516 PB - Royal Society of Chemistry (RSC) AN - OPUS4-40814 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, R. A1 - Fa, X. A1 - Yang, J. A1 - Cheng, Z. A1 - Ansari, A. A. A1 - Ou, Jun A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Preparation of core–shell structured NaYF4:Yb3+/ Tm3+@NaYF4:Yb3+/Er3+ nanoparticles with high sensitivity, low resolution and good reliability and application of their fluorescence temperature properties N2 - A series of NaYF4:Yb3+/Tm3+@NaYF4:Yb3+/Er3+ nanoparticles doped with Tm3+ and Er3+ were successfully prepared by the solvothermal method. Under 980 nm laser excitation, intense upconversion emission peaks of Tm3+ and Er3+ were observed for all samples. By doping Tm3+ and Er3+ with core–shell partitioning, not only a significant increase in fluorescence intensity could be achieved, but also simultaneous temperature measurements on multiple thermocouple energy levels could be realised. In addition, the temperature sensing performance of different thermocouple energy levels was also investigated, and it was found that the 3 F3 → 3 H6 and 1 G4 → 3 F4 thermocouple energy level pairs of Tm3+ were the best, with maximum absolute sensitivity and maximum relative sensitivity of up to 0.0250 K−1 and 2.155% K−1 respectively, higher than the sensitivity of other thermocouple energy levels. It has a temperature resolution of less than 0.0139 K, which is lower than that of most materials available today. By using this material as a probe to build a fiber optic temperature sensor platform, it was found to have reliable temperature measurement performance. KW - Flourescence KW - Optical probe KW - Sensor KW - Dye KW - Temperature KW - Nano KW - Particle KW - Upconversion KW - Lanthanide KW - Qantum yield KW - Quality assurance KW - Monitoring KW - Infrastructure PY - 2022 DO - https://doi.org/10.1039/d1ce01729b VL - 24 IS - 9 SP - 1752 EP - 1763 PB - RSC Publishing AN - OPUS4-54416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ahiboz, D. A1 - Andresen, Elina A1 - Manley, P. A1 - Resch-Genger, Ute A1 - Würth, Christian A1 - Becker, C. T1 - Enhanced photon upconversion using erbium-doped nanoparticles interacting with silicon metasurfaces N2 - Photon upconversion (UC) using trivalent erbium (Er+3) doped crystals is a promising concept to harness near infrared photons of the solar spectrum which cannot be directly absorbed by silicon solar cells. However, their UC efficiency at low-intensity 1 sun illumination is not relevant on device level so far. Exploiting giant near-field enhancement effects on metasurfaces is an appealing approach to enable efficient UC at low irradiance conditions. Here, we report on more than 1000-fold enhanced photon UC of NaYF4:Er+3 nanoparticles interacting with the near-fields supported by a silicon metasurface under 1550 nm excitation. T2 - 48th Photovoltaic Specialists Conference (PVSC) CY - Online meeting DA - 20.06.2021 KW - Nano KW - Nanomaterial KW - Upconversion nanoparticle KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Sensor KW - Excitation power density KW - Brightness KW - NIR KW - Mechanism KW - Modeling KW - Simulation KW - Energy transfer KW - Photonic crystal KW - Enhancement strategy PY - 2021 DO - https://doi.org/10.1109/pvsc43889.2021.9518495 SP - 1 EP - 3 PB - IEEE CY - Berlin AN - OPUS4-53786 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Würth, Christian A1 - Fischer, S. A1 - Grauel, Bettina A1 - Alivisatos, A. P. A1 - Resch-Genger, Ute T1 - Quantum Yields, Surface Quenching, and Passivation Efficiency for Ultrasmall Core/Shell Upconverting Nanoparticles N2 - We synthesized and characterized a set of ultrasmall hexagonal-phase NaGdF4: 20% Yb3+, 2% Er3+ upconversion nanoparticles with core diameters of 3.7 ± 0.5 nm. In order to assess passivation effects and the influence of possible core−shell intermixing and to identify optimum particle structures for combined imaging in the visible and near-infrared (vis−NIR: 410−850 nm) and short-wave infrared (SWIR: 1520 nm), NaYF4 shells of varying thicknesses (monolayer to 10 nm) were introduced and the influence of this parameter on the upconversion and downshifting photoluminescence of these particles was studied at different excitation power densities. This included excitation power-dependent emission spectra, slope factors, quantum yields, and excited state decay kinetics. These measurements revealed enhancement factors of the upconversion quantum yield of >10 000 in the low power region and an excitation power density-independent quantum yield of the downshifted emission at 1520 nm between 0.1 and 14%. The optimized shell thickness for combined vis and SWIR imaging was identified as 5 nm. Moreover, lifetimes and quantum yields can be continuously tuned by shell thickness which can be exploited for lifetime multiplexing and encoding. The fact that we did not observe a saturation of the upconversion quantum yield or the excited state decay kinetics with increasing shell thickness is ascribed to a strong intermixing of the active core with the inert shell during the shelling procedure. This indicates the potential of spectroscopic tools to detect cation intermixing. KW - Nanoparticle KW - Upconversion KW - Quenching PY - 2018 DO - https://doi.org/10.1021/jacs.8b01458 IS - 140 SP - 4922 EP - 4928 PB - American Chemical Society AN - OPUS4-45378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Meng, M. A1 - Zhang, R. A1 - Cheng, Z. A1 - Fa, X. A1 - Yang, J. A1 - Ansari, A. A. A1 - Ou, Jun A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Retraction: Effect of Ca2+ doping on the upconversion luminescence properties of NaYF4:Yb3+/Tm3+ nanoparticles and study of its temperature measurement performance N2 - Retraction of "Effect of Ca2+ doping on the upconversion luminescence properties of NaYF4:Yb3+/Tm3+ nanoparticles and study of its temperature measurement performance" by Mingzhou Meng et al., CrystEngComm, 2022, 24, 4887–4898, https://doi.org/10.1039/D2CE00562J. The Royal Society of Chemistry, with the agreement of the authors, hereby wholly retracts this CrystEngComm article due to concerns with the reliability of the data. PY - 2023 DO - https://doi.org/10.1039/d3ce90111d SN - 1466-8033 VL - 25 IS - 33 SP - 4768 PB - Royal Society of Chemistry CY - London AN - OPUS4-58494 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hodenius, M. A1 - Würth, Christian A1 - Jayapaul, J. A1 - Wong, J. E. A1 - Lammers, T. A1 - Gätjens, J. A1 - Arns, S. A1 - Mertens, N. A1 - Slabu, I. A1 - Ivanova, G. A1 - Bornemann, J. A1 - De Cuyper, M. A1 - Resch-Genger, Ute A1 - Kiessling, F. T1 - Fluorescent magnetoliposomes as a platform technology for functional and molecular MR and optical imaging N2 - Here, we present a detailed characterisation of rhodamine B-containing magnetoliposomes (FLU-ML), emphasising the dependence of their fluorescence properties on the presence of iron oxide cores, and the molar fraction of the fluorophore. The magnetoliposome types used exist as colloidally stable, negatively charged clusters with an average hydrodynamic diameter of 95 nm. The molar rhodamine B fractions were 0.67 % and 1.97 %. Rhodamine B normalised fluorescence, quantum yields and fluorescence lifetimes were substantially reduced by inner filter effects as the magnetoliposome concentration is increased, by increasing molar rhodamine B fraction, and by quenching originating from the iron oxide cores. MR relaxometry at 3 T revealed extremely high r2 relaxivities (440 to 554 s-1mM-1) and moderately high r1 values (2.06 to 3.59 s-1mM-1). Upon incubating human prostate carcinoma (PC-3) cells with FLU-ML, a dose-dependent particle internalisation was found by MR relaxometry. In addition, the internalised FLU-ML were clearly visible by fluorescence microscopy. At the FLU-ML concentrations used (up to 3 × 103 M Fe) cell viability was not substantially impaired. These results provide valuable insights on the fluorescence properties of bimodal magnetoliposomes and open promising perspectives for the use of these materials as a platform technology for advanced functional and molecular MR and optical imaging applications. KW - Fluorescent magnetoliposomes KW - Steady state and time resolved fluorometry KW - Quantum yield KW - Fluorescence lifetimes KW - MR relaxivities KW - PC-3 cells KW - Cell viability PY - 2012 DO - https://doi.org/10.1002/cmmi.467 SN - 1555-4309 SN - 1555-4317 VL - 7 IS - 1 SP - 59 EP - 67 PB - Wiley CY - Chichester AN - OPUS4-25577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, X.-X. A1 - Würth, Christian A1 - Zhao, L. A1 - Resch-Genger, Ute A1 - Ernsting, N.P. T1 - Femtosecond broadband fluorescence upconversion spectroscopy: improved setup and photometric correction N2 - A setup for fluorescence upconversion spectroscopy (FLUPS) is described which has 80 fs temporal response (fwhm) for emission in the spectral range 425–750 nm. Broadband phase matching is achieved with tilted gate pulses at 1340 nm. Background from harmonics of the gate pulse is removed and sensitivity increased compared to previous designs. Photometric calibration of the upconversion process is performed with a set of fluorescent dyes. For Coumarin 153 in methanol the peak position, bandwidth, and asymmetry depending on delay time are reported. KW - Calibration KW - Fluorescence spectroscopy KW - Fluorescence KW - Upconversion KW - Standard KW - Spectral responsivity KW - Time-resolved fluorescence KW - Quality assurance KW - Coumarin 153 KW - Solvation dynamics PY - 2011 DO - https://doi.org/10.1063/1.3597674 SN - 0034-6748 SN - 1089-7623 VL - 82 SP - 063108-1 EP - 063108-8 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-23886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Würth, Christian A1 - Pauli, Jutta A1 - Weigert, Florian T1 - Quantitative optical-spectroscopic characterization of luminescent nanomaterials - Photoluminescence Quantum Yields N2 - Accurate and quantitative photoluminescence measurements are mandatory for the comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters as well as for most applications relying on their luminescence features in the life and material sciences and nanobiophotonics. In the following, procedures for the determination of the spectroscopic key parameter photoluminescence quantum yield, i.e., the number of emitted per absorbed photons, in the UV/vis/NIR/SWIR are presented including pitfalls and achievable uncertainties and material-specific effects related to certain emitter classes are addressed. Special emphasis is dedicated to luminescent nanocrystals. T2 - International Workshop on "Emerging Nanomaterials for Displays and SSL" CY - Dresden, Germany DA - 11.11.2021 KW - Nano KW - Nanomaterial KW - Nanocrystal KW - Semiconductor quantum dot KW - Lanthanide KW - Photoluminescence KW - Quantum yield KW - Photophysics KW - Lifetime KW - Surface chemistry KW - Brightness KW - NIR KW - SWIR KW - Method KW - Uncertainty KW - Rreference material PY - 2021 AN - OPUS4-53783 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Characterisation of Particle based Fluorescent Biosensor Systems T2 - ANAKON 2009 CY - Berlin, Germany DA - 2009-03-17 PY - 2009 AN - OPUS4-19419 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, M. A1 - Zhang, R. A1 - Zhenlong, F. A1 - Yang, J. A1 - Ansari, A. A1 - Ou, Jun A1 - Würth, Christian A1 - Resch-Genger, Ute T1 - Retracted article: Effect of Ca2+ doping on the upconversion luminescence properties of NaYF4:Yb3+/Tm3+ nanoparticles and study of its temperature measurement performance N2 - A solvothermal method was used to prepare a series of Yb3+/Tm3+/Ca2+ co-doped NaYF4 nanoparticles with different Ca2+ contents. Strong upconversion blue fluorescence could be observed under 980 nm laser excitation of the samples. The effect of different Ca2+ contents on the luminescence intensity was investigated, and it was found that the UV-vis upconversion luminescence increased and then decreased with an increasing Ca2+ concentration during the increase of the Ca2+ content from 0 mol% to 25 mol%, reaching the strongest fluorescence at 15 mol%, which was up to about 28 times stronger than that without Ca2+ doping. Furthermore, the mechanism was investigated, and it was found that the doping of Ca2+ disrupted the symmetry of the crystal field, resulting in a significant enhancement of the overall fluorescence. Applied to fluorescence intensity ratio thermometry, the absolute and relative sensitivities are as high as 0.0418 K−1 and 2.31% K−1, respectively, with a minimum temperature resolution of 0.0129 K. KW - Sensor KW - Temperature KW - Lanthanide KW - Luminescence KW - Nanoparticles KW - Upconversion KW - Advanced materials PY - 2022 DO - https://doi.org/10.1039/D2CE00562J SN - 1466-8033 VL - 24 IS - 27 SP - 4887 EP - 4898 PB - Royal Society of Chemistry CY - London AN - OPUS4-56952 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -